Fesoterodine is [2-[(1R)-3-(Di(propan-2-yl)amino)-1-phenylpropyl]-4-(hydroxymethyl)phenyl]2-methylpropanoate and represented by formula (I).

The product is marketed in the form of fumarate salt. The current pharmaceutical product containing this drug is being sold by Pfizer using the trade name Toviaz, in the form of extended release oral tablets. Fesoterodine is cholinergic antagonist and muscarinic antagonist. Fesoterodine is rapidly de-esterified to its active metabolite, (R)-2-(3-diisopropylamino-1-phenylpropyl)-4-hydroxymethyl-phenol, or 5-hydroxy methyl tolterodine, which is a muscarinic receptor antagonist. Fesoterodine is used as Urinary Incontinence Products. It is used to treat overactive bladder.
Few processes for the synthesis of 3,3-diphenylpropylamine derivatives have been described in the literature.
Tolterodine and other 3,3-diphenylpropylamine analogs were first described in U.S. Pat. No. 5,382,600. Said patent described several methods for preparing tolterodine and its analogs generally based a process for the preparation of Tolterodine which is shown in the Scheme-I.

The main problem associated with this process is that it involves use of less economical reagent and which requires specific handling skill when used. Moreover, some of the reagents like Lithium aluminum hydride should be avoided while using at plant because it hazardously reacts towards water and being more hygroscopic in nature compared to other reducing reagents like sodium borohydride. Further use of pyridine is some time prone to hazardous and biologically nondegradable and therefore it is not environment friendly. Further use of boron tribromide is also non appropriate. All these drawbacks make the process less economical and unsuitable at industrial level.
U.S. Pat. No. 6,713,464 disclosed a variety of 3,3-diphenylpropylamine derivatives, processes for their preparation, pharmaceutical compositions in which they are present and method of use thereof. A process for the preparation of Fesoterodine which is shown in the Scheme-II.

The above processes for preparation of Fesoterodine require many number of steps and involve unfriendly reagents. The process is less economical, relatively less safe and time-consuming. Hence such technology is not readily suitable for commercial production.
WO2005012227 describes process for preparation of Fesoterodine from Tolterodine. But, This process involves preparation of resolved Tolterodine and then its benzylation increase the number of steps such as debenzylation to prepare tolterodine, resolution of tolterodine and then further benzylation to convert in R(+)benzyl tolterodine. Which further convert in to Fesoterodine.
Based on the aforementioned drawbacks, prior art processes find to be unsuitable for preparation of Fesoterodine at lab scale and commercial scale operations. Hence, a need still remains for an improved and commercially viable process of preparing pure Fesoterodine or a pharmaceutically acceptable salt thereof that will solve the aforesaid problems associated with process described in the prior art and will be suitable for large-scale preparation, in lesser reaction time, in terms of simplicity, purity and yield of the product.